Composition and method for low temperature deposition of silicon-containing films

ABSTRACT

This invention relates to silicon precursor compositions for forming silicon-containing films by low temperature (e.g., &lt;300° C.) chemical vapor deposition processes for fabrication of ULSI devices and device structures. Such silicon precursor compositions comprise at least one disilane derivative compound that is fully substituted with alkylamino and/or dialkylamino functional groups.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No. 10/699,079, filed Oct. 31, 2003, now U.S. Pat. No. 7,446,217, which is a continuation-in-part of U.S. patent application Ser. No. 10/294,431, filed Nov. 14, 2002, now U.S. Pat. No. 7,531,679 in the names of Ziyun Wang, Chongying Xu, Ravi K. Laxman, Thomas H. Baum, Bryan C. Hendrix, and Jeffrey F. Roeder, the entire contents of which are incorporated by reference herein in their entirety.

FIELD OF THE INVENTION

The present invention relates generally to the formation of silicon-containing films in the manufacture of semiconductor devices, and more specifically to compositions and methods for forming such films, e.g., films comprising silicon, silicon nitride (Si₃N₄), siliconoxynitride (SiO_(x)N_(y)), silicon dioxide (SiO₂), etc., low dielectric constant (k) thin silicon-containing films, high k gate silicate films and low temperature silicon epitaxial films.

DESCRIPTION OF THE RELATED ART

Silicon nitride (Si₃N₄) thin films are widely employed in the microelectronic industry as diffusion barriers, etch-stop layers, sidewall spacers, etc.

Deposition of silicon nitride films by chemical vapor deposition (CVD) techniques is a highly attractive methodology for forming such films. CVD precursors currently used include bis(tert-butylamino)silane (BTBAS) or silane/ammonia, but such precursors usually require deposition temperature higher than 600° C. for forming high quality Si₃N₄ films, which is incompatible with the next generation IC device manufacturing, where deposition temperature of below 500° C., and preferably about 450° C., is desired. Therefore, development of low-temperature silicon-containing CVD precursors is particularly desired.

Presently, hexachlorodisilane, Cl₃Si—SiCl₃, is being studied as a candidate precursor for low-temperature CVD formation of silicon nitride upon reaction with ammonia gas. The drawbacks of using hexachlorodisilane in CVD processes include: (i) formation of large amount of NH₄Cl during the process, which leads to the particle contamination and solid build-up in vacuum system and exhaust lines; (ii) possible chlorine incorporation in the chips, which could significantly reduce their life time and long-term performance. It is therefore desirable to develop new chlorine-free precursors that can be used for low-temperature CVD formation of silicon nitride.

SUMMARY OF THE INVENTION

The present invention relates generally to the formation of silicon-containing films, such as films comprising silicon, silicon nitride (Si₃N₄), siliconoxynitride (SiO_(x)N_(y)), silicon dioxide (SiO₂), etc., silicon-containing low k films, high k gate silicates, and silicon epitaxial films, among which silicon nitride thin films are preferred, in the manufacture of semiconductor devices, and more specifically to compositions and methods for forming such silicon-containing films.

The present invention in one aspect relates to a group of chlorine-free disilane derivatives that are fully substituted with alkylamino and/or dialkylamino functional groups and can be used as CVD precursors for deposition of silicon-containing thin films.

Such disilane derivative compounds can be represented by the general formula of:

wherein R₁-R₁₂ may be the same as or different from one another and each is independently selected from the group consisting of H, C₁-C₅ alkyl, and C₃-C₆ cycloalkyl.

Preferably, the disilane derivative compound of the present invention is characterized by a symmetrical structure in relation to the Si—Si bond. In one preferred embodiment of the present invention, such disilane derivative compound contains at least two alkylamino functional groups that are symmetrically distributed in relation to the Si—Si bond. Such disilane derivative compound may also contain two or more dialkylamino functional groups symmetrically distributed in relation to the Si—Si bond.

More preferably, such disilane derivative compound is selected from the group consisting of (NEt₂)₂(HNMe)Si—Si(HNMe)(NEt₂)₂, (HNBu^(t))₂(HNMe)Si—Si(HNMe)(HNBu^(t))₂, and (HNBu^(t))₂(NH₂)Si—Si(NH₂)(HNBu^(t))₂, wherein Et is used as the abbreviation of ethyl, Bu^(t) is used as the abbreviation of t-butyl, and Me is used as the abbreviation of methyl, consistently throughout herein.

Another aspect of the present invention relates to a method for forming a silicon-containing film on a substrate, comprising contacting a substrate under chemical vapor deposition conditions including a deposition temperature of below 550° C., preferably about 500° C., with a vapor of a disilane compound that is fully substituted with alkylamino and/or dialkylamino functional groups.

Still another aspect of the present invention relates to a method of making (NEt₂)₂(HNMe)Si—Si(HNMe)(NEt₂)₂, by reacting (NEt₂)₂(Cl)Si—Si(Cl)(NEt₂)₂ with excess H₂NMe.

Yet a further aspect of the present invention relates to a method of making (HNBu^(t))₂(HNMe)Si—Si(HNMe)(HNBu^(t))₂, by reacting (HNBu^(t))₂(Cl)Si—Si(Cl)(HNBu^(t))₂ with LiN(H)Me.

A still further aspect of the present invention relates to a method of making (HNBu^(t))₂(NH₂)Si—Si(NH₂)(HNBu^(t))₂, by reacting (HNBu^(t))₂(Cl)Si—Si(Cl)(HNBu^(t))₂ with LiNH₂.

A still further aspect of the present invention relates to a method of forming silicon-containing thin films on a substrate, by contacting the substrate under chemical vapor deposition conditions with a vapor of an above-described disilane derivative compound, or a mixture of two or more above-described disilane derivatives. Preferably, the deposition temperature is not higher than 550° C., more preferably not higher than 500° C., and most preferably not higher than 450° C.

Other aspects, features and embodiments of the invention will be more fully apparent from the ensuing disclosure and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a STA plot for (NEt₂)₂(HNMe)Si—Si(HNMe)(NEt₂)₂.

FIG. 2 is a STA plot for (HNBu^(t))₂(HNMe)Si—Si(HNMe)(HNBu^(t))₂.

FIG. 3 is a STA plot for (HNBu^(t))₂(NH₂)Si—Si(NH₂)(HNBu^(t))₂.

FIG. 4 is an X-ray crystal structure of the compound (HNBu^(t))₂(NH₂)Si—Si(NH₂)(HNBu^(t))₂.

DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS THEREOF

The present invention relates to silicon precursors for CVD formation of films on substrates, such as silicon precursors for forming low k dielectric films, high k gate silicates, low temperature silicon epitaxial films, and films comprising silicon, silicon oxide, silicon oxynitride, silicon nitride, etc., as well as to corresponding processes for forming such films with such precursors.

Disilane derivatives that are fully substituted with alkylamino and/or dialkylamino functional groups, free of any halogen-substitutes, are found particularly suitable for low-temperature deposition of silicon nitride thin films.

Such fully substituted disilane compound may be represented by the generic formula of:

wherein R₁-R₁₂ may be the same as or different from one another and each is independently selected from the group consisting of H, C₁-C₅ alkyl, and C₃-C₆ cycloalkyl.

The fully substituted disilane compounds of the above formula are advantageously characterized by a melting temperature of less than 100° C., and a vaporization temperature of less than 300° C. Moreover, such disilane compounds can be transported in vapor form at less than 300° C., with no or little (≦1%) residual material at atmospheric pressure. The silicon-containing films that can be formed using such disilane precursor compounds include low dielectric constant (k) thin films, high k gate silicates and silicon epitaxial films. In a particularly preferred embodiment of the invention, the films formed using such disilane precursors comprise silicon nitride.

Preferred disilane compounds of the above-described formula include those characterized by a symmetrical structure in relation to the Si—Si bond, such as (NEt₂)₂(HNMe)Si—Si(HNMe)(NEt₂)₂, (HNBu^(t))₂(HNMe)Si—Si(HNMe)(HNBu^(t))₂, and (HNBu^(t))₂(NH₂)Si—Si(NH₂)(HNBu^(t))₂, etc. More preferably, such disilane compounds contain at least two alkylamino functional groups and/or two or more dialkylamino functional groups that are symmetrically distributed in relation to the Si—Si bond. For example, both (HNBu^(t))₂(HNMe)Si—Si(HNMe)(HNBu^(t))₂ and (HNBu^(t))₂(NH₂)Si—Si(NH₂)(HNBu^(t))₂ contain four t-butylamino functional groups that are symmetrically distributed in relation to the Si—Si bond; (NEt₂)₂(HNMe)Si—Si(HNMe)(NEt₂)₂ contains two methylamino functional groups and four diethylamino functional groups that are symmetrically distributed in relation to the Si—Si bond.

FIG. 1 shows the STA plot for (NEt₂)₂(HNMe)Si—Si(HNMe)(NEt₂)₂, which has a melting temperature of about 81.7° C., and can be transported in its vapor form completely with almost no residual material at about 300° C. at atmospheric pressure or in a flow of inert gas.

FIG. 2 is the STA plot for (HNBu^(t))₂(HNMe)Si—Si(HNMe)(HNBu^(t))₂, showing an even lower melting temperature of about 34.0° C., with only 0.55% residual material when vaporized at about 250° C. at atmospheric pressure or in a flow of inert gas.

FIG. 3 is the STA plot for (HNBu^(t))₂(NH₂)Si—Si(NH₂)(HNBu^(t))₂, which has a melting temperature of about 72.1° C. and can be transported in its vapor form at about 250° C., with only 0.49% residual material noted at 500° C.

FIG. 4 further shows an X-ray crystal structure of the disilane derivative compound (HNBu^(t))₂(NH₂)Si—Si(NH₂)(HNBu^(t))₂.

Synthesis of several preferred disilane derivatives is described in the following examples:

Example 1 Synthesis of (NEt₂)₂(HNMe)Si—Si(HNMe)(NEt₂)₂

The disilane compound (NEt₂)₂(HNMe)Si—Si(HNMe)(NEt₂)₂ can be synthesized by reacting (NEt₂)₂(Cl)Si—Si(Cl)(NEt₂)₂ with excess amount of H₂NMe, according to the following equations: (NEt₂)₂(Cl)Si—Si(Cl)(NEt₂)₂+excess H₂NMe→(NEt₂)₂(HNMe)Si—Si(HNMe)(NEt₂)₂+2H₂NMe.HCl

Specifically, a 1 L flask was filled with a solution comprising 500 mL diethyl ether and 20 grams (48.2 mmol) of (NEt₂)₂(Cl)Si—Si(Cl)(NEt₂)₂. H₂NMe was bubbled into such solution. White precipitate was observed during the addition of H₂NMe. Approximately 20 grams of H₂NMe (644.25 mmol) was added into the 1 L reaction flask during a ten-hour period. The resulting mixture was filtered, and all volatile materials were removed from the filtrate under vacuum conditions. The crude yield was about 90%. Either vacuum distillation or low temperature crystallization is used to purify the end product. ¹H NMR (C₆D₆): δ 0.39 (br, 2H), 1.11 (t, 24H), 2.54 (d, 6H), 3.06 (q, 16H). ¹³C{¹H} NMR (C₆D₆): δ 14.8 (—CH₂CH₃), 28.2 (—CH₂CH₃), 38.3 (—HNCH₃). m/z: 332 [M⁺ —(—NEt₂)], 202 [M⁺ —(—Si(HNMe)(NEt₂)₂].

Example 2 Synthesis of (HNBu^(t))₂(HNMe)Si—Si(HNMe)(HNBu^(t))₂

The disilane compound (HNBu^(t))₂(HNMe)Si—Si(HNMe)(HNBu^(t))₂ can be synthesized by reacting (HNBu^(t))₂(Cl)Si—Si(Cl)(HNBu^(t))₂ with about 2 molar ratio of LiN(H)Me, according to the following equations: (HNBu^(t))₂(Cl)Si—Si(Cl)(HNBu^(t))₂+2LiN(H)Me→(HNBu^(t))₂(HNMe)Si—Si(HNMe)(HNBu^(t))₂+2LiCl

Specifically, a 250 mL flask was charged with a solution comprising 100 mL diethyl ether and 200.1 mL (1.6M, 32.2 mmol) of n-butyllithium hexanes solution. 1 gram of H₂NMe was then bubbled into such solution at 0° C. White precipitate material was formed immediately. Upon completion of this addition, the 250 mL reaction flask was allowed to warm up to room temperature and was stirred for about one hour. Subsequently, 5 grams of (HNBu^(t))₂(Cl)Si—Si(Cl)(HNBu^(t))₂ (12 mmol) in 40 mL diethyl ether was slowly added into the reaction flask, which was stirred overnight and then refluxed for addition four hours. The mixture was filtered at room temperature. 3.5 grams (72% yield) viscous liquid crude product was obtained after removing the volatiles from the filtrate. The end product is purified by recrystallization from hexanes solution at −25° C., and it has a melting temperature between 34° C. and 38° C. ¹H NMR(C₆D₆): δ 0.38 (br, 2H, H—NMe), 0.99 (br, 4H, H-Nbu^(t)), 1.31 (s, 36H), 2.66 (d, 6H), 3.06 (q, 16H). ¹³C{¹H} NMR(C₆D₆): δ 28.3 (—C(CH₃)₄), 34.2 (—HNCH₃), 49.4 (—C(CH₃)₃). m/z: 332 [M⁺ —(—HNBu^(t))], 202 [M⁺ —(—Si(HNMe)(HNBu^(t))₂].

Example 3 Synthesis of (HNBu^(t))₂(NH₂)Si—Si(NH₂)(HNBu^(t))₂

The disilane compound (HNBu^(t))₂(NH₂)Si—Si(NH₂)(HNBu^(t))₂ can be synthesized by reacting (HNBu^(t))₂(Cl)Si—Si(Cl)(HNBu^(t))₂ with about 2 molar ratio of LiNH₂, according to the following equations: (HNBu^(t))₂(Cl)Si—Si(Cl)(HNBu^(t))₂+2LiNH₂→(HNBu^(t))₂(NH₂)Si—Si(NH₂)(HNBu^(t))₂+2LiCl

Specifically, a 250 mL flask was charged with a solution comprising 100 mL monoglyme and 5 grams (12.0 mmol) of HNBu^(t))₂(Cl)Si—Si(Cl)(HNBu^(t))₂. 0.58 gram (25.2 mmol) LiNH₂ was added and heated to reflux for approximately four hours. All volatile material was removed from the resulting mixture under vacuum. Approximately 150 mL hexanes was used to extract the product. After filtration, the filtrate was concentrated to about 80 mL and stored in a freezer overnight. White crystal material was separated from the solution and dried under vacuum, resulting in about 60% yield. About 20% of such dried crystal material was further recovered in purified form through recrystallization. ¹H NMR (C₆D₆): δ 0.60 (br, 4H), 1.32 (s, 36H). ¹³C{¹H} NMR (C₆D₆): δ 34.2 (—C(CH₃)₄), 49.6 (—C(CH₃)₃). m/z: 232 [M⁺ —(—HNBu^(t))], 188 [M⁺ —(—Si(NH₂)(HNBu^(t))₂].

The disilane derivative compounds of the present invention as described hereinabove can be used, either separately or as mixtures, for low-temperature CVD deposition of various silicon-containing films, including silicon nitride thin films, consistent with the disclosure in U.S. patent application Ser. No. 10/294,431 for “Composition and Method for Low Temperature Deposition of Silicon-Containing Films Including Silicon Nitride, Silicon Dioxide and/or Silicon-Oxynitride” filed on Nov. 14, 2002, the content of which is incorporated by reference in its entirety for all purposes.

Preferably, one or more of the above-described disilane derivatives are first dissolved in a hydrocarbon solvent or a solvent system that comprises at least one hydrocarbon solvent. Suitable hydrocarbon solvents for the practice of the present invention include, but are not limited to, alkylamines such as HN^(i)Pr₂, wherein ^(i)Pr is used herein as the abbreviation of isopropyl. Such solution containing the disilane derivative(s) of the present invention is vaporized at a temperature that is not higher than 300° C., preferably not higher than 150° C., and more preferably about 120° C., and transported to the deposition chamber together with a carrier gas, such as helium or argon, for contact with a heated substrate surface to deposit the silicon-containing thin films.

Silicone nitride deposition processes using one or more disilane derivatives of the present invention are described in the following examples:

Example 4 Silicon Nitride Deposition with (HNEt)₃Si—Si(HNEt)₃ and HN^(i)Pr₂

A solution of the compound (HNEt)₃Si—Si(HNEt)₃ was prepared at a concentration of 0.4M in a hydrocarbon solvent and at a concentration of 0.036M in HN^(i)Pr₂. These solutions were metered at 0.0127 ml/minute and 0.167 ml/minute, respectively into a vaporizer that was held at temperature of 120° C. and had a flow of 10 standard cubic centimeters per minute (sccm) of He as a carrier gas. The vapor was mixed with 50 sccm or 25 sccm, respectively of NH₃ in a showerhead vaporizer device that was maintained at 120° C. and thereby dispersed over the surface of a heated Si(100) wafer. The chamber pressure was maintained at 10 Torr to 60 Torr during deposition. The growth rate of the silicon nitride films ranged from 72 Å/minute to 34 Å/minute depending upon pressure, temperature, NH₃ rate, and precursor rate.

Chemical analysis of the films, by a combination of RBS (Rutherford Backscattering), HFS (Hydrogen Forward Scattering), and NRA (Nuclear Reaction Analysis), and spectroscopic ellipsometry revealed that (HNEt)₃Si—Si(HNEt)₃ with HN^(i)Pr₂ deposits films with decreased hydrogen impurity and increased carbon impurity for the same ultra-violet absorption edge (UVAE), deposition rate, and index of refraction as shown in Table 1 below.

TABLE 1 Film composition for various deposition conditions using the precursor (HNEt)₃Si—Si(HNEt)₃ with the nitrogen source and solvent HN^(i)Pr₂ NH₃ HN^(i)Pr₂ T Rate UVAE H C (sccm) (sccm) (° C.) P (torr) (Å/min) n (eV) (at %) (at %) N/Si 25 25 550 20 41 1.92 4.13 16.5 10.8 1.23 50 0 550 60 44 1.85 4.31 19.0 5.6 1.24 25 25 550 10 41 1.98 3.91 14.7 11.0 1.10 50 0 550 20 36 1.94 3.82 15.0 6.9 1.12

Example 5 Silicon Nitride Deposition with (NEt₂)₂(HNMe)Si—Si(HNMe)(NEt₂)₂

A solution of the compound of Example 1, (NEt₂)₂(HNMe)Si—Si(HNMe)(NEt₂)₂, was prepared at a concentration of 0.4M in a hydrocarbon solvent. This solution was metered at 0.0127 ml/minute or 0.025 ml/minute into a vaporizer that was held at temperature of 120° C. and had a flow of 10 standard cubic centimeters per minute (sccm) of He as a carrier gas. The vapor was mixed with 50 sccm or 300 sccm of NH₃ in a showerhead vaporizer device that was maintained at 120° C. and thereby dispersed over the surface of a heated Si(100) wafer. The chamber pressure was maintained at 5 Torr to 60 Torr during deposition. The growth rate of the silicon nitride films ranged from 20 Å/minute to 2 Å/minute depending upon pressure, temperature, NH₃ rate, and precursor rate.

Chemical analysis of the films, by a combination of RBS (Rutherford Backscattering), HFS (Hydrogen Forward Scattering), and NRA (Nuclear Reaction Analysis), and spectroscopic ellipsometry revealed that (NEt₂)₂(HNMe)Si—Si(HNMe)(NEt₂)₂ deposits films with increased the N/Si ratio along with higher ultra-violet absorption edge (UVAE) and index of refraction and decreased the impurity carbon and hydrogen content as shown in Table 2 below.

TABLE 2 Film composition for various deposition conditions using the precursor (NEt₂)₂(HNMe)Si—Si(HNMe)(NEt₂)₂ Rate NH3 T P (Å/ UVAE H C (sccm) (° C.) (torr) min) n (eV) (at %) (at %) N/Si 300 600 20 8 1.96 5.21 9.5 1.7 1.36 50 550 5 13 1.99 4.00 10.0 8.5 1.20

Example 6 Silicon Nitride Deposition with (HNBu^(t))₂(HNMe)Si—Si(HNMe)(HNBu^(t))₂

A solution of the compound of Example 2, (HNBu^(t))₂(HNMe)Si—Si(HNMe)(HNBu^(t))₂, was prepared at a concentration of 0.4M in a hydrocarbon solvent. This solution was metered at 0.0127 ml/minute or 0.025 ml/minute into a vaporizer that was held at temperature of 120° C. and had a flow of 10 standard cubic centimeters per minute (sccm) of He as a carrier gas. The vapor was mixed with 50 sccm or 300 sccm of NH₃ in a showerhead vaporizer device that was maintained at 120° C. and thereby dispersed over the surface of a heated Si(100) wafer. The chamber pressure was maintained at 20 Torr to 60 Torr during deposition. The growth rate of the silicon nitride films ranged from 30 Å/minute to 2 Å/minute depending upon pressure, temperature, NH₃ rate, and precursor rate.

Chemical analysis of the films, by a combination of RBS (Rutherford Backscattering), HFS (Hydrogen Forward Scattering), and NRA (Nuclear Reaction Analysis), and spectroscopic ellipsometry revealed that (HNBu^(t))₂(HNMe)Si—Si(HNMe)(HNBu^(t))₂ deposits films with super-stoichiometric N/Si ratio along with high ultra-violet absorption edge (UVAE) independent of process condition. Index of refraction and the impurity carbon and hydrogen contents were reduced as shown in Table 3 below.

TABLE 3 Film composition for various deposition conditions using the precursor (HNBu^(t))₂(HNMe)Si—Si(HNMe)(HNBu^(t))₂ Rate NH3 T P (Å/ UVAE H C (sccm) (° C.) (torr) min) n (eV) (at %) (at %) N/Si 50 550 20 13 1.83 5.14 12.5 6.9 1.47

Example 7 Silicon Nitride Deposition with (HNBu^(t))₂(NH₂)Si—Si(NH₂)(HNBu^(t))₂

A solution of the compound of Example 3, (HNBu^(t))₂(NH₂)Si—Si(NH₂)(HNBu^(t))₂, was prepared at a concentration of 0.4M in a hydrocarbon solvent and at a concentration of 0.072M in HN^(i)Pr₂. These solutions were metered at 0.0127 ml/minute or 0.025 ml/minute or 0.05 ml/minute or 0.07 ml/minute into a vaporizer that was held at temperature of 120° C. and had a flow of 10 standard cubic centimeters per minute (sccm) of He as a carrier gas. The vapor was mixed with 38 sccm to 300 sccm of NH₃ in a showerhead vaporizer device that was maintained at 120° C. and thereby dispersed over the surface of a heated Si(100) wafer. The chamber pressure was maintained at 4 Torr to 60 Torr during deposition. The growth rate of the silicon nitride films ranged from 68 Å/minute to 7 Å/minute depending upon pressure, temperature, NH₃ rate, and precursor rate.

Chemical analysis of the films, by a combination of RBS (Rutherford Backscattering), HFS (Hydrogen Forward Scattering), and NRA (Nuclear Reaction Analysis), and spectroscopic ellipsometry revealed that (HNBu^(t))₂(NH₂)Si—Si(NH₂)(HNBu^(t))₂ deposits films with high N/Si ratio along with high ultra-violet absorption edge (UVAE) independent of process condition. Index of refraction and the impurity carbon and hydrogen contents were reduced as shown in Table 4 below.

TABLE 4 Film composition for various deposition conditions using the precursor (HNBu^(t))₂(NH₂)Si—Si(NH₂)(HNBu^(t))₂ NH3 HN^(i)Pr₂ T Rate UVAE H C (sccm) (sccm) (° C.) P (torr) (Å/min) n (eV) (at %) (at %) N/Si 38 12 550 20 29 1.83 5.01 15.5 7.4 1.42 30 0 500 4 14 1.74 5.70 19.5 3.6 1.19

Example 8 Silicon Nitride Deposition with (HNBu^(t))₂(NH₂)Si—Si(NH₂)(HNBu^(t))₂ and (HNEt)₃Si—Si(HNEt)₃

A solution of two compounds: 0.0576M (HNBu^(t))₂(NH₂)Si—Si(NH₂)(HNBu^(t))₂, 0.0144M (HNEt)₃Si—Si(HNEt)₃ was prepared in HN^(i)Pr₂. This solution was metered at 0.0138 ml/minute into a vaporizer that was held at temperature of 120° C. and had a flow of 10 standard cubic centimeters per minute (sccm) of He as a carrier gas. The vapor was mixed with 275 sccm of NH₃ in a showerhead vaporizer device that was maintained at 120° C. and thereby dispersed over the surface of a heated Si(100) wafer. The chamber pressure was maintained at 10 Torr to 60 Torr during deposition. The growth rate of the silicon nitride films ranged from 33 Å/minute to 7 Å/minute depending upon pressure and temperature.

Chemical analysis of the films, by a combination of RBS (Rutherford Backscattering), HFS (Hydrogen Forward Scattering), and NRA (Nuclear Reaction Analysis), and spectroscopic ellipsometry revealed that the combination of (HNBu^(t))₂(NH₂)Si—Si(NH₂)(HNBu^(t))₂ with (HNEt)₃Si—Si(HNEt)₃ deposits films whose properties intermediate to those deposited from the two precursors independently. Films with high N/Si ratio along with high ultra-violet absorption edge (UVAE), high index of refraction and very low impurity carbon and hydrogen contents were deposited as shown in Table 5 below.

TABLE 5 Film composition for various deposition conditions using the precursor (HNBu^(t))₂(NH₂)Si—Si(NH₂)(HNBu^(t))₂ with (HNEt)₃Si—Si(HNEt)₃ NH3 HN^(i)Pr₂ T Rate UVAE H C (sccm) (sccm) (° C.) P (torr) (Å/min) n (eV) (at %) (at %) N/Si 275 25 550 20 11 1.90 4.86 10.5 3.1 1.42

While the invention has been described herein with reference to various specific embodiments, it will be appreciated that the invention is not thus limited, and extends to and encompasses various other modifications and embodiments, as will be appreciated by those ordinarily skilled in the art. Accordingly, the invention is intended to be broadly construed and interpreted, in accordance with the ensuing claims. 

1. A composition comprising a disilane compound that is fully substituted with alkylamino (—NHR) and/or dialkylamino (—N(R₂)) functional groups, wherein each R is independently selected from C₃-C₆ cycloalkyl.
 2. The composition of claim 1, wherein the alkylamino and/or dialkylamino functional groups are symmetrically distributed in relation to the Si—Si bond.
 3. The composition of claim 1, comprising alkylamino functional groups that are symmetrically distributed in relation to the Si—Si bond.
 4. The composition of claim 1, comprising dialkylamino functional groups that are symmetrically distributed in relation to the Si—Si bond.
 5. The composition of claim 1, wherein the disilane compound has a melting point below 100° C.
 6. The composition of claim 1, having a volatilization temperature of less than 300° C.
 7. The composition of claim 1, further comprising a hydrocarbon solvent medium.
 8. The composition of claim 7, wherein the hydrocarbon solvent medium comprises HN^(i)Pr₂. 